1. Field of the invention.
This invention relates to relief valves and more particularly to a combination double acting valve responsive to vacuum and/or pressure to prevent excess vacuum or pressure of fluid in a vessel.
2. Description of the prior art.
Relief valves are well known in industry and are calibrated to open at a predetermined pressure However I do not know of any prior patent disclosing a combination double acting relief valve biased open by fluid pressure above or below a predetermined value in a vessel.
This invention accomplishes this purpose.